ANSI Common Lisp  1 Introduction 1.5 Conformance 1.5.2 Conforming Programs
1.5.2.1 Use of Implementation-Defined Language Features
Note that conforming code may rely on particular
implementation-defined values or features. Also note that the
requirements for conforming code and conforming implementations do not
require that the results produced by conforming code always be the
same when processed by a conforming implementation. The results may be the
same, or they may differ.
Conforming code may run in all conforming implementations, but might
have allowable implementation-defined behavior that makes it
non-portable code.
For example, the following are examples of forms that are conforming, but
that might return different values in different implementations:
(evenp most-positive-fixnum)  implementation-dependent
(random) implementation-dependent
(> lambda-parameters-limit 93) implementation-dependent
(char-name #\A) implementation-dependent
1.5.2.1.1 Use of Read-Time Conditionals
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